JP2000333692A - Production of xylooligosaccharide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive recovery and purification method for xylooligosaccharide included in the drainage after treatment of paper-making pulp with hemicellulase, and a method for inhibiting the deterioration of bleaching properties in the oxygen bleaching step that is mainly caused by the xylooligosaccharide liberated in the bleaching drainage. SOLUTION: This process for producing xylooligosaccharide comprises the step where the reaction filtrate is collected from the step of treatment of the pulp starting from lignocellulose material with hemicellulase, the step where the concentrate including xylooligosaccharide is obtained from the reaction filtrate by the membrane filtration, and the step where the xylooligosaccharide is separated and recovered from the concentrate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing xylo-oligosaccharides from a pulp hemicellulase-treated reaction solution in a pulp production process using a lignocellulose material as a raw material.

[0002]

2. Description of the Related Art Xylooligosaccharides are useful saccharides used in lactic acid bacteria drinks, chocolates, etc., which are certified as foods for specified health use, having a function of keeping the stomach in good condition through the selective growth promoting effect of intestinal bacteria. And medicine,
In the field of sanitary products, it is also used as an emulsifier and a moisturizing ingredient for the skin. In addition, it is used not only for human food but also as an additive for livestock feed.

[0003] In general, oligosaccharides used for specified health foods are mostly intestinal-controlling, that is, reduce the number of Escherichia coli, which is a "bad intestinal bacterium", and the number of bacteria of the genus Clostridium, which is an intestinal spoilage fermentative bacterium. It has the effect of relatively increasing the number of bifidobacteria called "good intestinal bacteria". For example, wheat bran is a polysaccharide composed of hemicellulose having xylan as a main chain, and is added to food as a food having an intestinal action as a hardly decomposable plant fiber.

[0004] It is said that the intestinal action of wheat bran is derived from xylo-oligosaccharides degraded by intestinal bacteria in the intestine. Xylooligosaccharides derived from wheat bran promote the selective growth of bifidobacteria, a good intestinal bacterium,
On the other hand, it is also said that the number of Escherichia coli, which is a bad intestinal bacterium, is relatively reduced. Escherichia coli and intestinal putrefactive fermenters are known to produce carcinogenic substances while growing in the intestine. It is important if you have.

[0005] It is said that the longer the chain length, the better the selective growth promoting effect obtained by ingesting xylo-oligosaccharides. In particular, trimeric or higher xylo-oligosaccharides are effective for selective growth. The xylo-oligosaccharides currently on the market are made from herbs such as wheat bran and corn cob, but the xylan backbone in these herbaceous plants is branched from other sugars such as glucuronic acid into the side chains. I have. Oligosaccharides containing only xylose as a constituent sugar from xylan having a large number of side chains can produce only those having a relatively small degree of polymerization. At present, most of the oligosaccharides constituting commercially available xylo-oligosaccharides are mainly composed of dimers, and development of xylo-oligosaccharides having a higher degree of polymerization than dimers is desired.

[0006] Xylooligosaccharides are produced from xylan, one of the main constituents of plants. Espart and stalk of tobacco are known as straight-chain xylan consisting of xylose only, but as xylan in industrially usable form, arabinoxylan contained in wheat fuma, corn cob, etc. obtained as a by-product of cereal production Glucurono arabinoxylan mainly contained in conifers, glucuronoxylan of broadleaf trees, and the like are known. These industrially usable forms of xylan include arabinose other than xylose, glucuronic acid,
-O-methylglucuronic acid, glucose, galactose, etc., and the constituent sugar composition of xylose and other saccharides differs depending on the type of plant.

As a method for producing xylan, Patent No. 14
As described in JP-A-6374, bagasse containing a large amount of pentosan, grasses, legumes, and flaxaceous plants are steamed under high pressure in the presence of an organic acid solution such as acetic acid, and the poorly soluble materials present in the raw materials are dissolved. Pentosan is soluble, weakens tissues other than vascular bundles, and can be subjected to a known pulping method such as a soda method, an alkaline sulfurous acid method, or a sulfate method on a fiber bundle obtained by pulverizing and washing the same, whereby pentosan can be fractionated. It is shown. Xylose is also abundant in wood, and is a major component of xylan in total weight of about 6 to 10% for softwood and about 20% for hardwood [Wood Chemistry, Nobuhiko Migita et al. Ed., Kyoritsu Shuppan p.73 (1968)]. Extraction of xylan in these woods to produce xylooligosaccharides, xylose, and xylitol has also been performed.

[0008] Pulp is currently produced mainly from wood chips by chemical treatment or mechanical treatment. The remaining constituents of lignocellulosic material, especially pulp that is a cellulose component from wood chips, are mainly lignin and hemicellulose, which are released into the pulp drainage. Techniques for isolating specific components from pulp effluent and using them for foods or food additives have been put to practical use. In the old days, vanillin was produced by oxidizing the effluent of sulfite pulp with air or oxygen at around 160 ° C. under alkaline conditions.

Further, xylose has been produced from hemicellulose released in the effluent of the pulping step by the pre-hydrolysis method during the production of kraft pulp (Japanese Patent Publication No. Sho 4).
3-731). In addition, yeast has been produced by using a large amount of sugar contained in the effluent of sulfite pulp as a culture medium to produce seasoning components such as nucleic acid contained in the yeast itself or as a composition thereof. Another method for producing protein from sulfite pulp effluent (JP-A-51-10)
No. 1193) and a method for producing alcohol (Japanese Patent Application Laid-Open No. 56-144742).

[0010] Treating the pulp with xylanase comprises:
Viikari et al. [L. Viikari et al., Biotechnol. Pulp Pa
per Ind. (Stockholm) pp. 67-69 (1986)], stating that the bleachability of pulp is improved. Mora et al. Reported that treating pulp with xylanase was effective in improving the strength of the pulp. Among them, xylose and xylooligosaccharides up to octamer were contained in the reaction filtrate obtained by treating kabakraft pulp with xylanase. (F. Mora et al., J. WoodChem. Tec
hnol., vol. 6, pp. 147-165 (1986)]. Senior et al. Also state that xylose and xylooligosaccharides are contained in the reaction filtrate obtained by treating aspen kraft pulp with xylanase [DJ Senior et al, Biotechno
l. Lett., vol. 10, pp. 907-912 (1988)]. However, none of these reports mentions the recovery of xylo-oligosaccharides from the pulp enzyme treatment reaction filtrate.

On the other hand, as a method for producing a xylo-oligosaccharide, JP-A-53-35005 (corresponding to US Pat. No. 4,181,796) is added to a plant raw material by adding acetic acid.
A method is described in which xylan and xylan fragments extracted with water are separated from monosaccharides and other impurities by treatment with pressurized saturated steam at a temperature of 60 to 230 ° C. According to this method, xylan and xylan fragments can be efficiently purified by an OH-type strongly basic ion exchange resin and ultrafiltration. Also, JP-A-61-242.
According to 592, xylan is treated with xylanase produced by a microorganism of the genus Bacillus, and as a method for producing xylo-oligosaccharide from the reaction filtrate, xylanase is heated and inactivated and then filtered to obtain a transparent reaction filtrate. It is described that a syrup can be obtained by concentrating this and a powder product can be obtained by freeze-drying.

Similarly, according to JP-A-63-112797, as a method for recovering xylo-oligosaccharides from a reaction filtrate obtained by treating hardwood xylan with xylanase derived from Trichoderma, decolorization with activated carbon and removal of activated carbon with a filter press are described. Then, the sugar adsorbed on the activated carbon is recovered with 15% ethanol, treated with an ion exchange resin of Amberlite IR-120B and Amberlite IR-410, desalted, and then enriched in xylobiose by membrane concentration using a reverse osmosis membrane. It has been shown that xylo-oligosaccharides can be obtained.

However, any of these reports,
An inexpensive method for recovering and purifying xylo-oligosaccharides from a reaction filtrate obtained by reacting a chemical pulp with hemicellulase is not described. The xylooligosaccharide found in the reaction filtrate obtained by reacting pulp with hemicellulase is described in the above-mentioned JP-A-63-1988.
It is costly and impractical to recover and purify according to the method disclosed in Japanese Patent No. 112979. The reason for this is that the pulp enzymatically treated effluent has a large capacity and a low sugar content, and the pulp enzymatically treated effluent contains various kinds of lignin, cellulose, and hemicellulose generated during the digestion and oxygen exposure processes. The main reason is that impurities such as organic acids are present in large amounts. That is, the amount of activated carbon and ion exchange resin required for preparative purification is large, and the concentration by the reverse osmosis membrane is large, and the amount of drainage is large, and large amounts of insoluble components such as lignin are included. There was a problem that needed.

In addition, general raw materials for the production of xylo-oligosaccharides include xylan in industrially usable form, such as wheat bran obtained as a by-product of cereal production, arabinoxylan contained in corn cob, and glucuronoxylan of hardwood. . These raw materials are extracted according to the above-described method, and treated with a hemicellulase such as xylanase to obtain a xylo-oligosaccharide having a xylo-oligosaccharide as a constituent from a monomer to about a 10-mer, mainly about a monomer to a pentamer. Manufacturing. These industrially available forms of xylan include arabinose other than xylose, glucuronic acid, 4-o-methylglucuronic acid,
It contains glucose, galactose, etc., and also contains a large amount of monosaccharides (for example, JP-A-4-53801).
Reference). In order to obtain a xylo-oligosaccharide consisting of pure xylose alone, more precise purification must be performed, and an inexpensive method for producing this saccharide has been desired.

[0015] Xylanase treatment of kraft pulp is known to allow for bleaching chemical depletion in bleaching sequences using chemicals. In the xylanase treatment, xylan in the pulp is hydrolyzed by xylanase, so that a large amount of xylose and xylo-oligosaccharide are released into the wastewater in the system in the bleaching step. In the paper industry, the treated water used in one step in the bleaching sequence is used in the preceding bleaching step in order to reduce the amount of process water used. Therefore, the water used during the step before the enzyme stage contains xylan decomposed products such as xylose and xylo-oligosaccharide released by xylanase.

These xylose and xylooligosaccharides are
Since it has a reducing group at the terminal, the aldehyde group is oxidized in an oxidative bleaching step such as oxygen bleaching, and becomes a carboxylic acid, a further oxidized furan derivative and a colored furan condensate, and consumes a bleaching chemical. Therefore, it is necessary to add bleaching chemicals in an amount consumed by these sugars. In addition, in oxygen bleaching performed under highly alkaline conditions, it is necessary to increase the alkali addition rate in order to compensate for the pH lowered by the carboxylic acid generated by oxidation of the aldehyde group.

One of the methods of not returning xylose or xylo-oligosaccharides generated by the xylanase treatment to the preceding bleaching step is to remove these reducing sugars and return the treated water containing no reducing sugars to the preceding stage. . However, since pulp wastewater is generated in large quantities as described above,
It is considered that a large amount of equipment is required for the ordinary reverse osmosis membrane method and the like, and no inexpensive treatment method has been reported.

[0018]

DISCLOSURE OF THE INVENTION The present inventors have focused on xylo-oligosaccharides in pulp effluent, and as a result of intensive studies, have found that xylo-oligosaccharides are present in the pulp effluent in combination with some substance. (Hereinafter, "xylo-oligosaccharide complex"
And a method for producing xylo-oligosaccharides at low cost by concentration using a reverse osmosis membrane or a membrane having a higher molecular weight cut-off than a reverse osmosis membrane and acid treatment. Accordingly, an object of the present invention is to provide an inexpensive method for recovering and purifying xylo-oligosaccharides contained in the wastewater of paper pulp after hemicellulase treatment. Another object of the present invention is to prevent the bleachability of the oxygen bleaching process from being deteriorated mainly due to xylo-oligosaccharides released into the bleaching effluent by the hemicellulase treatment.

[0019]

The present invention for achieving the above object includes the following inventions. (1) A step of obtaining a concentrated solution containing a xylo-oligosaccharide complex having a molecular weight of 1500 or more from a reaction filtrate obtained from a hemicellulase treatment step of pulp using a lignocellulose material as a raw material by a membrane filtration method. A method for producing xylo-oligosaccharides, comprising a step of separating and recovering xylo-oligosaccharides.

(2) A coagulant selected from an inorganic coagulant and a polymer coagulant is added to a reaction filtrate obtained from a hemicellulase treatment step of a pulp using a lignocellulose material as a raw material, and the formed floc is formed. The step of removing by filtration, the step of obtaining a concentrated solution containing the xylo-oligosaccharide complex by a membrane filtration method from the filtrate obtained from the step of removing by filtration,
A method for producing xylooligosaccharides, comprising a step of separating and collecting xylooligosaccharides from the concentrated solution.

(3) The method for producing a xylo-oligosaccharide according to the above item (1) or (2), wherein the hemicellulase is xylanase. (4) The method for producing a xylo-oligosaccharide according to any one of (1) to (3), wherein the pulp using the lignocellulose material as a raw material is a chemical pulp.

(5) The method for producing a xylo-oligosaccharide according to any one of the above items (1) to (4), wherein the chemical pulp is a hardwood kraft pulp. (6) The method for producing a xylo-oligosaccharide according to any one of (1) to (5), wherein the chemical pulp is pulp after oxygen bleaching.

(7) In the step of separating and recovering the xylo-oligosaccharide from the concentrated solution containing the xylo-oligosaccharide complex having a molecular weight of 1500 or more, the concentrated solution containing the xylo-oligosaccharide complex is adjusted to pH 2 to 4, To 200 ° C, preferably 105 to 170 ° C, more preferably 110 to 125 ° C
(1) to (6), wherein the mixture is subjected to a heat treatment for 1 minute to 120 minutes to obtain a mixture containing dimers to 10-mers of xylose.
The method for producing a xylo-oligosaccharide according to any one of the above items.

(8) The step of obtaining a mixture containing the dimer to the xylose of xylose by the heat treatment is carried out by a film treatment of the xylose dimer to a xylose dimer following the heat treatment.
(7) The method for producing a xylooligosaccharide according to (7), which is a step of separating and obtaining a mixture of xylooligosaccharides containing a 10-mer. (9) The method for producing a xylo-oligosaccharide according to the item (8), wherein the xylo-oligosaccharide separated and recovered by the membrane treatment is further decolorized and purified with an ion exchange resin.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The reaction filtrate to be treated by the present invention may be a reaction filtrate obtained by treating any of chemical pulp and mechanical pulp as hemicellulase as pulp as a lignocellulose substance in the hemicellulase treatment step. Among the chemical pulp, a reaction filtrate obtained from a hemicellulase treatment step of kraft pulp, soda pulp, and particularly hardwood kraft pulp is preferable. Further, the reaction filtrate from the hemicellulase treatment step of the digested pulp of hardwood kraft pulp or the pulp obtained by oxygen bleaching the digested pulp is desirable.

In the hemicellulase treatment step for producing the reaction filtrate used in the present invention, any hemicellulase can be used as long as it has xylanase activity. For example, commercially available enzyme preparations such as cartazyme, pulpzyme, eco-pulp, and sumyzyme, Trichoderma, Thermomyces, Aureobasidium, Streptomyces, Aspergillus, Clostridium,
Xylanases produced by microorganisms such as Bacillus, Thermotoga, Thermoascus, Cardoserum, and Thermomonospora can be used.

According to the present invention, the composition ratio of xylose and xylooligosaccharide generated in the treatment reaction filtrate obtained by treating pulp with hemicellulase varies depending on the type of enzyme used, and those containing a large amount of xylose and those containing a large amount of xylobiose The xylotriose may be various, such as Bacillus sp.S-21
When 13 strains of xylanase (see JP-A-8-224081) are used, the composition ratio of xylose and xylo-oligosaccharide generated in the treatment reaction filtrate is the highest in the tetramer and the lowest in the monomer ratio. Produce sugar. In particular, when hardwood kraft pulp is used, there are almost no constituent sugars such as glucose and arabinose, and xylose is almost 10%.
It has the characteristic of being close to 0%.

The xylo-oligosaccharide released from the pulp hemicellulase-treated reaction filtrate is filtered through a 5 μm filter to remove insoluble components, and then passed through a reverse osmosis membrane. Was detected, and the total sugar contained was about 30% of the total sugar amount in the original reaction filtrate. On the other hand, these oligosaccharides and monosaccharides are slightly detected in the reverse osmosis membrane concentrate, but about 70% of them were mostly recovered as xylo-oligosaccharide complexes.
In addition to a simple reverse osmosis membrane, a membrane for nanofiltration called a loose RO in which the membrane itself is charged can be used. This is a membrane having a membrane rejection of about 50% of salt, but can be used in exactly the same manner as a reverse osmosis membrane. At that time, the total sugar recovery rate is about 70%, which is the same as when a reverse osmosis membrane is used. %Met. Ultrafiltration can also be used, but the total sugar recovery is about 30%.

The xylo-oligosaccharide complex contained in the pulp enzymatic reaction solution can be concentrated by physical or chemical treatment such as evaporation, coagulation and precipitation, and solvent extraction. However, it is industrially advantageous to concentrate the xylo-oligosaccharide through a membrane that allows the xylo-oligosaccharide to pass through and the xylo-oligosaccharide complex to remain in the membrane and be concentrated. One of the reasons is that the operation cost is relatively low and it is not necessary to use a special chemical substance such as a solvent, and various inorganic substances contained in the enzyme reaction solution together with the xylo-oligosaccharide, for example, This is because low molecular organic substances derived from monosaccharides or oligosaccharides such as glucose, xylose and arabinose, organic acids, lignin, etc., sodium carbonate, sodium thiosulfate, etc. can be separated and removed by this method.

Generally, when a membrane element such as a reverse osmosis membrane or an ultrafiltration membrane is operated, a colloidal substance or a suspended substance present in raw water adheres and accumulates on the membrane surface, and the filtration ratio increases with time. The resistance increases and the permeation flux decreases. Since it is practically important to minimize the performance degradation of such membranes and modules and to operate it stably for a long time, turbidity treatment by coagulation sedimentation, filter filtration, etc. is performed as pretreatment. I have. Lignin, defoamer, and fine insoluble components, which are difficult to remove by filter filtration alone, are suspended in the pulp hemicellulase treatment reaction filtrate, which causes a decrease in permeation flux when performing membrane concentration. . Therefore, as a pretreatment before membrane concentration, a flocculant is added to the reaction filtrate, thereby removing the flocculated floc formed and obtaining a clear filtrate, thereby preventing a decrease in permeation flux at the time of membrane concentration. can do.

As the coagulant to be added, an inorganic coagulant such as a sulfuric acid band or polyaluminum chloride, or a polymer coagulant such as a polyacrylamide or polyamidine coagulant or a natural coagulant such as chitosan. Molecular flocculants can be used. The amount of the coagulant added is 500 to 1000 ppm in the case of a sulfate band with respect to the reaction filtrate.
(After adding the sulfuric acid band, adjust the pH to 7.5 with caustic soda.)
5 to 30 pp in the case of a cationic synthetic polymer flocculant
In the case of m and chitosan, an aggregated floc can be obtained at about 30 to 60 ppm, but it is preferable to determine the amount to be added according to the water quality of the reaction filtrate. The obtained floc can be removed by centrifugation or filtration using a precoat filter, bag filter, filter press, or the like. The reaction filtrate, which has been clarified by the flocculant treatment and the filtration operation, has a higher clarity than the reaction filtrate of only the filtration operation without adding the flocculant treatment, and a decrease in permeation flux in membrane concentration. Is prevented.

Xylooligosaccharides are dimer or higher oligomers. The molecular weight of xylose was 150 and 2
The dimer is 282, the trimer is 414, and the molecular weight increases by 132 for each additional xylose residue,
The decamer is 1338. The concentrated xylo-oligosaccharide complex is a mixture of the xylo-oligosaccharide with a polymer substance generated in the course of digestion of any substance, possibly a lignin or lignocellulose substance, or a hemicellulose-derived furan derivative, in the pulp enzyme reaction solution. It is thought to be forming.

The total sugar contained in the membrane concentrate consists almost exclusively of xylose, and the acid is added to the membrane concentrate to adjust the pH below 5, and the xylooligosaccharide is released by heating at a high temperature. Can be. The acid in this case is not particularly limited, and any acid can be used. For example, in addition to mineral acids such as sulfuric acid and hydrochloric acid, oxalic acid,
An organic acid such as acetic acid is exemplified. P during acid treatment of concentrate
H is preferably 2 to 4, and more preferably pH is 3.
Range from 5 to 4.0. When the pH is 1.5 or less, hydrolysis to xylose is promoted, and the recovery of xylooligosaccharide is reduced. When the pH is 5 or more, 150
At temperatures up to about ° C, release of xylo-oligosaccharides is not promoted.

The heating temperature required for releasing the xylo-oligosaccharide is not particularly limited as long as it is a temperature at which the xylo-oligosaccharide is released, but the temperature is preferably from 100 to 200 ° C., particularly preferably from 105 to 170 ° C. Preferred temperatures are from 110 ° C to 125 ° C. At processing temperatures below 100 ° C., xylooligosaccharides are not released from the xylooligosaccharide complex. On the other hand, when the temperature exceeds 170 ° C., the decomposition reaction to xylose, which is a monosaccharide, is accelerated, and the yield of xylooligosaccharide is reduced. The pressure during the reaction is 5k from atmospheric pressure.
g / cm ² .

The treatment time required for releasing the xylo-oligosaccharide varies depending on the amount, pH and temperature of the acid to be added. For example, when the pH is adjusted to 3.5 with sulfuric acid, 120 hours is required.
C. and 15 minutes are preferred. In practice, a composition having a desired xylo-oligosaccharide composition ratio can be obtained by setting appropriate conditions in consideration of these pH, temperature, and time conditions. It is also possible to further increase the ratio of xylose or xylobiose by applying an appropriate xylanase or hemicellulase.

The xylo-oligosaccharide composition after the acid treatment still contains insoluble substances such as lignin and coloring substances. Insoluble matter can be removed by processing such as centrifugation, filtration with a filter, or filtration with a filter cloth. The method for removing impurities such as dissolved coloring substances is not particularly limited, and a method using a conventionally known activated carbon, a strong basic anion exchange resin such as Amberlite, a weak basic anion, etc. The method using an exchange resin, a strongly acidic cation exchange resin, a weakly acidic cation exchange resin, and a membrane filtration method may be repeated, or a combination thereof.
For example, the xylo-oligosaccharide complex after the heat treatment is filtered through a filter cloth to remove insolubles, then treated with an ultrafiltration membrane, and the permeated fraction is treated with a weakly basic and strongly basic ion exchange resin. Then, the non-adsorbed fraction is treated with a small amount of activated carbon to decolorize, and then desalted with an amphoteric ion exchange resin for desalting to obtain a purified oligosaccharide. By these series of treatments, it is possible to obtain about 70 kilograms of xylooligosaccharide from 1000 L of the raw material solution after the acid treatment.

Further, since most of the monosaccharides such as xylose, glucose, and arabinose contained in the filtrate of the enzyme treatment reaction of pulp are removed by first performing membrane filtration, the membrane concentrate is subjected to heat treatment. Is characterized in that the content ratio of these monosaccharides is small. This feature is advantageous for the expression of a selective growth inhibitory effect of Escherichia coli.

According to the present invention, an organic substance such as lignin and sugar in the filtrate can be removed by filtering the enzyme-treated reaction filtrate with an ultrafiltration membrane. Generally, in the bleaching sequence of pulp, water is basically used repeatedly in countercurrent washing. Therefore, by removing the lignin and organic substances originally contained in the first step using the filtrate, the efficiency of the first step processing, for example, the oxygen bleaching step, digestion, etc., is increased, and the brightness of the pulp is improved. The use of chemicals and energy can be reduced. Further, by removing organic substances such as lignin and sugar in the filtrate by a membrane, it becomes possible to reduce the amount of organic substances in the bleaching wastewater to be sent to the subsequent bleaching sequence together with the pulp. This makes it possible to reduce the amount of COD in the wastewater discharged from the final bleaching sequence.

[0039]

The present invention provides a method for producing a xylo-oligosaccharide fraction from a reaction filtrate obtained by subjecting pulp to xylanase or a hemicellulase containing reaction.
According to the present invention, a composition in which the constituent sugar of xylooligosaccharide is only xylose, the content of xylose which is a monosaccharide is small, and the content of oligosaccharides of trimer or more, especially tetramer or more than dimer, is large. It is also easy to produce a xylo-oligosaccharide composition having the same.

[0040]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples. All percentages shown below are by weight unless otherwise specified, and the pulp addition ratio is the ratio of volume to absolute dry weight of pulp.

Example 1 Preparation of Concentrated Sugar Solution Using a mixed hardwood chip consisting of 70% domestic hardwood chip and 30% eucalyptus wood as raw materials, a factory-made unbleached kappa number of 20.1 and a pulp viscosity of 41 cps by kraft cooking. Pulp was obtained. Next, oxygen delignification was performed to obtain oxygen delignified pulp having a kappa number of 9.6 and a pulp viscosity of 25.1 cps. The pulp was filtered off and washed with a 100-mesh filter cloth, the pulp concentration was adjusted to 10%, the pH was adjusted to 8 by adding dilute sulfuric acid, and then Bacillus sp. Xylanase produced by the deposited strain FERM BP-5264) was added to the pulp at a rate of 1 unit / g.
Treated at 0 ° C. for 120 minutes. After the treatment, pulp residue and the like are separated by filtration through a 100-mesh filter cloth, and the total sugar concentration is 370.
1050 L containing 0 mg / L (3900 in total sugar amount)
g) was obtained.

Subsequently, a reverse osmosis membrane (manufactured by Nitto Denko: RO NTR-
7410, membrane quality: sulfonated polyethersulfone, salt rejection 10%: Usually, the molecular weight cut off is 1000 or more. ) And concentrated 40 times by volume. This concentrated liquid has a total sugar amount of 2700 g, and a total sugar recovery rate of 7
It was 0%. The xylooligosaccharide and the xylooligosaccharide complex in the sample were analyzed by ion chromatography (ion chromatography column: PA-10) manufactured by Dionex. The results are shown in Table 1 and FIG. In FIG. 1A, the vertical axis indicates the amount of electricity (nanocoulomb: nC), and the horizontal axis indicates the elution time (minute). In addition, from the left, xylose, monosaccharide (6 minutes), dimer (9.2 minutes), and trimer (1
0.3 min), tetramer (11.4 min), pentamer (12.5 min)
Min), (hereinafter, a hexamer, a heptamer, and so on), and a xylo-oligosaccharide complex (23.8 minutes). FIG.
As is clear from (a) and Table 1, the content of xylooligosaccharide in the concentrate was low.

Reference Example 1 The concentrated sugar solution obtained in Example 1 was adjusted to pH 5.0 with oxalic acid and acetic acid, respectively, and reacted at 121 ° C. for 1 hour. As a result, it was found that xylo-oligosaccharides were not newly generated as compared with the control in the treatment reaction using any of the acids.
Table 1 shows the results for oxalic acid, and similar results were obtained for acetic acid.

Reference Example 2 The concentrated sugar solution obtained in Example 1 was subjected to pH adjustment using sulfuric acid.
Was adjusted to 5.0, reacted at 100 ° C. for 1 hour, and analyzed in the same manner as in Example 1. Also in this treatment reaction, it was found that xylo-oligosaccharide was not newly generated.

Example 2 Sulfuric acid was appropriately added to 1,000 ml of the concentrated sugar solution obtained in Example 1 to adjust the pH to 3.5. Thereafter, the concentrated sugar solution was reacted at 121 ° C. for 1 hour. The reaction product is converted to a column for ion chromatography (Dionex: PA-10
As a result of analysis by ion chromatography using), it was found that xylo-oligosaccharides (dimers to 10-mers) were produced at a higher concentration than the control (untreated sugar solution) (Table 1). The results are shown in FIG. FIG.
(B) shows a chromatogram by ion chromatography of a 1/100 dilution of a sample heat-treated at 121 ° C. for 1 hour at pH 3.5. The vertical axis represents the quantity of electricity (n
C), and the horizontal axis shows the elution time (minutes). Also, from the left, xylose, monosaccharide (6 minutes), dimer (9.2 minutes), trimer (10.3 minutes), and tetramer (11.
4 minutes), a pentamer (12.5 minutes), (hereinafter, a hexamer, a 7-mer,...) And a xylo-oligosaccharide complex (2
3.8 minutes). As is clear from FIG. 1B and Table 1, xylo-oligosaccharides (dimers to 10-mers) are produced at a higher concentration than the control (untreated sugar solution) in FIG. 1A. It has been found.

Examples 3 to 5 The same procedure as in Example 2 was carried out except that oxalic acid, acetic acid and hydrochloric acid were used instead of sulfuric acid as the acid for changing the pH of the concentrated sugar solution obtained in Example 1 to 3.5. The reaction was carried out to prepare a xylo-oligosaccharide sugar solution. As a result, a xylo-oligosaccharide sugar solution (a solution of a dimer to a 10-mer) could be obtained in the same manner as in the preparation with sulfuric acid (Table 1).

Reference Examples 3 to 5 The concentrated sugar solution obtained in Example 1 was adjusted to pH 1 with sulfuric acid (Reference Example 3), oxalic acid (Reference Example 4) and hydrochloric acid (Reference Example 5). After adjusting to 5, the mixture was reacted at 121 ° C. for 1 hour and analyzed in the same manner as in Example 1. As a result, in the treatment reaction using any of the acids, the xylo-oligosaccharide was decomposed by the acid and the molecular weight was reduced to xylose. (Table 1).

Example 6 The concentrated sugar solution obtained in Example 1 was adjusted to pH 3.5 with sulfuric acid, and reacted at 155 ° C. for 1 hour.
The analysis was performed in the same manner as in Example 1. Short-chain oligosaccharides such as xylose and xylobiose increased. Table 1 shows the results for sulfuric acid. Similar results were obtained when oxalic acid was used instead of sulfuric acid.

Examples 7 to 10 The concentrated sugar solution obtained in Example 1 was adjusted to pH 3.5 with sulfuric acid and oxalic acid, respectively, and then reacted at 121 ° C. for 30 minutes. Minutes and 15 minutes. afterwards,
As a result of analyzing the newly formed xylo-oligosaccharide in the same manner as in Example 2, it was found that the xylo-oligosaccharide was generated in the same reaction time as when treated at 121 ° C. for 60 minutes in both the reaction times of 30 minutes or 15 minutes. (Table 1).

[0050]

[Table 1]

Example 11 Purification of Xylooligosaccharide Produced by Acid Treatment (1) Oxalic acid was appropriately added to the saccharide solution obtained in Example 1 to adjust the pH of the solution to 3.5. Then 121
Heat treatment was performed at 60 ° C. for 60 minutes to prepare a xylo-oligosaccharide sugar solution (total sugar concentration: 140 mg / ml). Insolubles contained in the prepared sugar solution were removed by filtration with a filter. Thereafter, 10 ml of this sugar solution was subjected to ultrafiltration using an ultrafiltration membrane having a molecular weight cut-off of 8000 to obtain 4 ml of a passing fraction.
The total sugar content of this flow-through fraction was 280 mg. Next, 4 ml of the passing fraction was subjected to 30 mg of a strongly basic ion exchange resin (manufactured by Rohm and Haas: Amberlite GC-400type2).
)), The total sugar content after the treatment was 26
0 mg. Finally, activated carbon (manufactured by Wako Pure Chemical Industries) and amphoteric ion exchange resin for desalination (manufactured by Rohm and Haas:
Decolorization using 30mg each of Amberlite MB3)
And desalting were successively performed by a batch method to obtain a final purified xylooligosaccharide solution. FIG. 2 shows a chromatogram of the 1/300 dilution obtained by ion chromatography. At this time, the total sugar amount was 113 mg. The final recovery was about 40% when the permeate after the ultrafiltration membrane treatment was 100% (Table 2). The impurity concentration in the purified xylo-oligosaccharide was 0.9%. In FIG. 2, the contents of each peak and the definitions of the vertical and horizontal axes are the same as in FIG.

[0052]

[Table 2]

Example 12: Purification of xylo-oligosaccharide after acid treatment (2) 250 ml of saccharide solution of xylo-oligosaccharide complex (106 mg / ml) prepared in the same manner as in Example 11, 26.5 g as total sugar amount Activated carbon (manufactured by Wako Pure Chemical: product number 037-0)
2115) (inner diameter 50 mm, length 200 mm). Thereafter, an attempt was made to recover xylo-oligosaccharides using pure water and 25% ethanol as elution solvents. First, when pure water was used as the eluate, no xylo-oligosaccharide was recovered. Therefore, next
Xylooligosaccharides adsorbed on activated carbon were eluted using 5% ethanol. The xylo-oligosaccharide recovered after the elution was desalted by a batch method using an amphoteric ion exchange resin (manufactured by Rohm and Haas: MB3) to obtain a purified xylo-oligosaccharide. The xylo-oligosaccharide recovered at this time was 5.5 g (Table 3).

[0054]

[Table 3]

Example 13: Purification of xylo-oligosaccharide after acid treatment (3) 10 ml of a xylo-oligosaccharide conjugate solution (117 mg / ml) prepared in the same manner as in Example 11 and 1.2 g as a total sugar amount Strongly acidic ion exchange resin (ROHM &
A column (inner diameter: 36 mm, length: 150 mm) packed with Haas Co .: Amberlite 200C was loaded. After recovering the xylo-oligosaccharide that has passed through the column, a weakly basic ion exchange resin (manufactured by Rohm and Haas: IRA67)
) Was loaded on a similar column. After concentration, the xylo-oligosaccharide obtained by passing through the column was added with 80 mg of activated carbon (manufactured by Wako Pure Chemical Industries, product number: 037-02115) to the xylo-oligosaccharide solution, stirred at 60 ° C for 1 hour, and decolorized. . After stirring, the activated carbon was filtered through a 0.22 μm membrane filter to obtain a purified xyloligosaccharide solution. 280 and 250 for the purified xylooligosaccharide solution
No absorption at a wavelength of nm was observed, and the ultraviolet absorbing substance contained in the xylo-oligosaccharide solution after the acid treatment was removed. The residual ratio of the ash was 0.1% or less based on the xylo-oligosaccharide solution after the acid treatment as a starting material. At this time, the recovery of xylooligosaccharide was 70.8% (Table 4).

[0056]

[Table 4]

Example 14 Unbleached pulp from a factory having a kappa number of 20.1 and a pulp viscosity of 41 cps was obtained by kraft cooking from a mixed hardwood chip comprising 70% of domestic hardwood chips and 30% of eucalyptus wood as a raw material. Next, oxygen delignification was performed to obtain oxygen delignified pulp having a kappa number of 9.6 and a pulp viscosity of 25.1 cps. The pulp was washed, the pulp concentration was adjusted to 10%, and the pH was adjusted to 8 by adding dilute sulfuric acid. Then, Bacillus sp. S-2113 strain (a strain deposited by the Institute of Biotechnology, Industrial Technology Research Institute, Ministry of International Trade and Industry) FER
MBP-5264) was added at a rate of 1 unit / g pulp, followed by treatment at 60 ° C. for 60 minutes. After the treatment, it was washed with a displacement press washing machine to obtain a washing filtrate. The total sugar concentration of the obtained washing filtrate was 1,700 mg / L.

2,000 L of the obtained washing filtrate was applied to a back filter (ISP FILT) having a micron rate of 10 μm.
ERS Pte Ltd) to remove insoluble components. At this time, 79 ppm of an insoluble component remained in the filtrate that had been subjected to the back filter filtration with respect to SS: 350 ppm of the washing filtrate. The amount of insoluble components in the filtrate was confirmed by measuring the SS concentration of the filtrate. 200 ml of each filtrate was added to a glass filter (ADVANT).
After filtration through an EC GA100 filter (diameter: 47 mm), the insoluble components captured by the filter were dried at 105 ° C. for 1 hour, and the dry weight was measured.

Next, 15 ppm of an acrylamide-based flocculant (Acofloc C492UH: Mitsui Scitech) was added as a cationic polymer flocculant to the 2000 L of the filtrate obtained in the same manner. Agitation formed flocculated flocs. After forming flocculated floc, it is filtered through a bag filter with a micron rate of 10 μm,
A clear filtrate was obtained. In the filtrate after the bag filter filtration, 11 ppm of insoluble components remained. Similarly, 2
To 000 L of the washing filtrate, 50 ppm of chitosan (Kimitsukitosan L: Kimitsu Chemical Industry) as a natural polymer flocculant was added to the washing filtrate, followed by stirring to form an aggregated floc. After forming flocculated flocs, micron rate 10μm
To obtain a clear filtrate. At this time, 13 ppm of insoluble components remained in the filtrate.
No sugar was lost due to the filtration of the flocculated floc. Further, even when 50 ppm of an anionic or nonionic polymer flocculant was added to the washing filtrate, flocculated flocs could not be formed (Table 5).

As described above, three types of washing filtrates were used.
After obtaining the pretreated filtrate,
Each solution was subjected to a reverse osmosis membrane (NITTO DENKO: RONTR-7
450, membrane quality: sulfonated polyethersulfone, food
Salt rejection 50%, membrane area: 6.5m^Two-2)
Liquid temperature 50 ° C, inlet operation pressure 10-20kgf / cm
^TwoUnder operating conditions of a flow rate of 1400 to 1800 L / hr,
It concentrated to 20 times the product ratio. Inlet operation pressure is 2kgf / h
cm^TwoPressurized. Filter by 10μ bag filter
Reverse osmosis in the treated filtrate from which insoluble components have been removed only by excessive operation
Permeation flux at the start of concentration by the membrane: 39 L / (hr.
m^Two), The flux at the end of the 20-fold concentration is 7 L /
(Hr.m^Two), And the permeation flux is reduced by 80% or more.
Was.

On the other hand, in the treated filtrate to which a cationic polymer flocculant (Acofloc 492UH: Mitsui Cytec) was added and the flocculated floc was removed with a 10 μ bag filter, the permeation flux at the start of concentration by the reverse osmosis membrane: 38 L /
(Hr.m ² ), the permeation flux at the end of the 20-fold concentration was 30 L / (hr.m ² ), and the permeation flux decreased only by 21%. Similarly, in the treated filtrate obtained by adding a natural polymer flocculant (Kimitsukitosan L: Kimitsu Chemical Industry) and removing flocculated floc by a 10 μ bag filter, the permeation flux at the start of concentration by the reverse osmosis membrane: 36 L / ( hr.m
² ), the flux at the end of the 20-fold concentration is 28 L /
(Hr.m ² ), the reduction rate of the permeation flux was 22% (FIG. 3). At this time, the total sugar amount contained in 100 L of a 20-fold concentrated liquid was about 2700 g with respect to 3400 g of the total sugar contained in 2000 L of the washing filtrate.
And the total sugar recovery was 80%.

Next, sulfuric acid was appropriately added to the obtained concentrated solution to adjust the pH to 3.5, and reacted at 121 ° C. for 1 hour. As a result of analyzing the reaction product by ion chromatography, it was confirmed that xylo-oligosaccharides (dimer to 10-mer) were produced at a high concentration (FIG. 4). Even if the floc formed by the addition of the flocculant is removed as a pretreatment of the concentration operation by the membrane, the composition of the obtained xylo-oligosaccharide does not change.

[0063]

[Table 5]

[0064]

According to the present invention, xylooligosaccharides containing xylose dimers to decamers can be supplied at low cost. In addition, xylooligosaccharides having a high proportion of xylooligosaccharides of 3 or more can be supplied. Furthermore, lignin and organic substances contained in the effluent are removed by membrane filtration of the pulp enzyme-treated effluent, so that the pulp bleachability during the pulp manufacturing process can be improved.

[Brief description of the drawings]

FIG. 1 is a chromatogram of components in a xylanase-treated reaction filtrate of hardwood kraft pulp, which was subjected to heat treatment after concentration.

FIG. 2 is a chromatogram of a purified xylo-oligosaccharide component.

FIG. 3 is a diagram showing a permeate flux of a treated filtrate over time in membrane concentration.

FIG. 4 is a diagram showing a chromatogram of xylo-oligosaccharide purified after concentrating and acid-treating a filtrate subjected to aggregation treatment.

Claims (6)

[Claims] 1. A step of obtaining a concentrated solution containing a xylo-oligosaccharide complex by a membrane filtration method from a reaction filtrate obtained from a hemicellulase treatment step of pulp using a lignocellulosic material as a raw material, and then obtaining a xylo-oligosaccharide from the concentrated solution A process for separating and recovering xylo-oligosaccharides. 2. A coagulant selected from an inorganic coagulant and a polymer coagulant is added to a reaction filtrate obtained from a hemicellulase treatment step of pulp using a lignocellulose material as a raw material. Removing, a step of obtaining a concentrated solution containing a xylo-oligosaccharide complex from the filtrate obtained by the filtration removing step by a membrane filtration method, and then separating and recovering the xylo-oligosaccharide from the concentrated solution. A method for producing a xylo-oligosaccharide. 3. The method for producing a xylo-oligosaccharide according to claim 1, wherein the hemicellulase is a xylanase. 4. The pulp using the lignocellulosic material as a raw material is a chemical pulp.
13. The method for producing a xylo-oligosaccharide according to the above item. 5. The method for producing a xylo-oligosaccharide according to claim 4, wherein the chemical pulp is a hardwood kraft pulp. 6. The step of separating and recovering xylo-oligosaccharides from the concentrate containing the xylo-oligosaccharide complex comprises adjusting the concentrate containing the xylo-oligosaccharide complex to a pH of 2 to 4,
The production of a xylooligosaccharide according to any one of claims 1 to 5, which is a step of heating the mixture at 100 to 170 ° C for 1 to 120 minutes to obtain a mixture containing xylose dimers to 10-mers. Method.